1. Field of the Invention
The present invention relates to bonding tools or bonding wedges of the type used in manual or automatic wire and tab bonders to attach an electrical conductor to a target, pad or terminal on a substrate, a PC board or other type of component carrier. More particularly, the present invention relates to a novel thermosonic wedge bonding tool adapted to be clamped in an ultrasonic transducer at an inclined angle so that the working face of the bonding wedge is displaced laterally and out from under the ultrasonic transducer providing access to the bonding area.
2. Description of the Prior Art
Heretofore, bonding wedges were known. Early discrete semiconductors had their wires electrically connected to carriers employing bonding wedges before bonding capillaries were developed. Single point wedge bonding tools are still employed in some Tape Automated Bonding (TAB) applications in preference to gang bonding tools. In the mid-1960s wedge bonding tools incorporated into the tools an inclined funnel or wire feed which enabled wire bonders to make first and second bonds without losing the fine wire from the tool.
Heretofore, wedge bonding tools were manufactured with a working face on the bonding tool which was substantially orthogonal to the vertical axis of the tool when mounted in a transducer or other type of tool holder. This arrangement is known to obscure the line of sight of a pattern recognition system (PRS) which is employed to locate the position of a semiconductor device and the bonding pads located thereon. It is the present practice to locate the bonding targets on a semiconductor device while not obscured by the bonding tool and its holder prior to performing a bonding operation. When a subsequent operation is being performed on or at the bonding target area, it is necessary to remove the object being wire bonded from its work station and reposition the object at a second work station. Alternatively, the work station must be movable to a second of two predetermined positions. In either event a considerable amount of time is lost and the cost of special fixtures may be required to assure proper post wire bonding operations.
It would be desirable to provide a wedge bonding tool and tool holder which avoids the problems described above when attempting to perform a second operation at the same location where a wire bond is being or has just been made.